Exchange coupling in MBE grown MnPt/NiFe bilayers

Exchange anisotropy in MnPt(30 nm)/NiFe(5 nm) bilayers was investigated for films grown by the MBE method on MgO(001) and SrTiO3(001) substrates. Duri ng the deposition, a static magnetic field of 100 Oe was applied in the fil m plane, In-situ reflection high-energy electron diffraction observations a nd ex-situ X-ray diffraction measurements revealed that the MnPt layers hav e chemical order and have(100) orientation which is an uncompensated plane of antiferromagnetic spin alignment. The bilayers whose MnPt layer was grow n on NiFe layer were found to have an exchange anisotropy field (H-ex) of 2 20 Oe (corresponding exchange anisotropy energy of J = 0.084 erg/cm(2)) and a low coercivity (H-c) of 43 Oe, while the bilayers whose NiFe layer was g rown on MnPt layer show very small H-ex and a large H-c.